1. Field of the Invention
This invention relates to the diagnosis of abnormal conditions in the lungs, and to a catheter by which to conduct bronchoalveolar lavage. More particularly the present invention relates to a method and apparatus for conducting bronchoalveolar lavage without the use of a bronchoscope.
2. Background Art
The technique of bronchoalveolar lavage has become common in the diagnosis of infections and other abnormalities in the alveoli at the terminus of the bronchiole in the lungs of a patient. In bronchoalveolar lavage, occasionally referred to as "BAL", a sterile fluid is infused in aliquots of about 30 ml. each through the upper respiratory system of a patient into the portion of the lungs thereof designated for study. The fluid infused is then aspirated and cultured and examined in order to isolate and identify infections, fungi, cells, and other signs of inflammation thusly flushed from the walls of the alveoli. Only about 40-60% of each infused aliquot can be aspirated. Thus in studies which require large volumes of aspirated fluid, a total infusion of from 30 to about 500 ml. may be required. A helpful background statement on the nature and useful findings related to the use of bronchoalveolar lavage is the American Thoracic Society, "Clinical Role of Bronchoalveolar Lavage in Adults with Pulmonary Disease", 142 AMERICAN REVIEW OF RESPIRATORY DISEASE, 481-486 (1990).
In order to effect the infusion of solution, it has in the past been the practice to utilize a bronchoscope to visually observe the advancement of a catheter through the upper respiratory system of a patient and the branching of the bronchi into a selected bronchiole. During this advancement process, the size of the air passage through which the distal tip of the bronchoscope is advanced gradually decreases until the distal tip of the bronchoscope wedges within the walls of a single bronchiole. This wedge is visually inspected using the bronchoscope, and thereafter the infusion and aspiration of solution is effected through the working lumen of the bronchoscope.
Drawbacks arise, however, in relation to the use of a bronchoscope in this procedure. First, the bronchoscope itself is a very expensive piece of equipment. As a result, it is not practical to dispose of the device following a single use. Instead the bronchoscope must be reused in order to distribute its expense over a number of procedures. Routine heat based sterilization cannot be used, however. Instead procedures must be employed which are particularly adapted to the delicate nature of the materials comprising the bronchoscope. These sterilization procedures are approximately 24 hours in duration, so that a single costly bronchoscope can be utilized at a given medical establishment only once a day. Thus, a plurality of bronchoscopes must be maintained by a medical establishment if the establishment is to have the opportunity to perform bronchoalveolar lavage more than once a day.
In addition to being extremely delicate in the face of normal sterilization conditions, bronchoscopes are very susceptible to breakage through incorrect use. Like the device itself, repairs on the bronchoscope are extremely expensive. A reference discussing the sources of damage to flexible fiber optic bronchoscopes is Mehta, et al., "The High Price of Bronchoscopy: Maintenance and Repair of the Flexible Fiber Optic Bronchoscope", 98 CHEST 448-54 (Aug. 1984), which is incorporated herein by reference.
Recent literature has forecast a rise in the frequency with which medical practitioners can be expected to resort to the use of bronchoalveolar lavage. The increased incidence of acquired immune deficiency syndrome (AIDS) and other therapeutic-related immunocompromising treatments, such as chemotherapy, gives rise to a large number of patients susceptible to multiple and exotic lung infections. An accurate diagnosis of the identity of these infections is essential, if the patient is to be effectively medicated. Typical of the literature discussing efforts at isolating lung infections in AIDS and other immunocompromised patients are the following:
Caughley, et al., "Non-Bronchoscopic Bronchio Alveoli Lavage for the Diagnosis of Pneumocystitis Carinii Pneumonia in the Acquired Immune Deficiency Syndrome", 88 CHEST 659-62 (Nov. 1985). PA1 Sobonya, et al., "Detection of Fungi and other Pathogens in Immunocompromised Patients by Bronchio Alveoli Lavage in an Area Endemic for Coccidioidomycosis", 97 CHEST 1349-55 (Jun. 1990). PA1 Guerra, et al., "Use of Bronchio Alveoli Lavage to Diagnose Bacterial Pneumonia in Mechanically Ventilated Patients", 18 CRITICAL CARE MEDICINE 169-73 (1990).
Some difficulties have also been experienced in effecting a clear diagnosis of conditions in the lung due to contamination of the equipment for conducting the bronchoalveolar lavage as the distal end of that equipment is passed through the upper respiratory system of a patient to the lung segment selected for study. In the process of that passage, the exterior of the distal end of the catheter by which infusion and aspiration is actually effected becomes contaminated with micro-organisms in the upper respiratory system of the patient. As a result, the fluid samples aspirated from the lungs thereafter are frequently compromised by cultures of organisms not actually located in the alveoli.
When a bronchoscope is not utilized, problems have been experienced in locating the distal tip of the sampling catheter in a specific preselected lung to be studied, placement in the left lung being particularly difficult due to inherent anatomical structure of the bronchi. Fluoroscopic and X-ray methods for verifying the location of a distal tip can to an extent be useful in assisting and directing the distal tip into a specific preselected lung, but these methods are totally incapable of replacing the primary value of bronchoscope use, namely the verification of distal tip wedging in a bronchi of the patient to the extent required for successful infusion and aspiration of fluid. Fluoroscopic and X-ray methods for effecting placement are also complicated to utilize, and may be limited by availability to large medical institutions.
A further problem which may occur during bronchoscopy is oxygen desaturation within the lungs. People who are restricted in their respiratory capacity, such as people with lung disease or those in an active pneumonia situation, may have a difficult time in maintaining their oxygen saturation throughout the bronchoalveolar lavage procedure. As such, supplemental oxygen must be provided. Currently, the patient may receive supplemental oxygen either by a nasal cannula or by an oxygen catheter which is slid through one of the nostrils and placed at the back of the throat above the vocal chords. With each added need for oxygen, the rate of flow of the supplemented oxygen may be increased from two liters to four liters, four liters to six, six liters to eight, and so on. Unfortunately, from increasing oxygen flow arises increased turbulence and irritation, along with the possibility that there may still be a transient drop in oxygen saturation even with the increased flow. This may occur as oxygen may be wasted along the passageway through the nose and the mouth and so on, before reaching the lungs. Therefore, in the prior art, oxygen insufflation cannot be executed with efficiency and success during the bronchoalveolar lavage procedure.